H. M. Fraser

22026 Background: Efforts have been undertaken to find new ways to target tumor growth such as inhibition of angiogenesis. One of the main angiogenic regulators is vascular endothelial growth factor (VEGF). Thus, targeting VEGF by application of VEGF- antibodies has become an approach in anti-angiogenic therapy. Recently, we showed that the Renin-Angiotensin-System (RAS) not only controls the vascular tone but also regulates angiogenesis via influencing VEGF in breast cancer cells. Now, this further study was performed in order to investigate, whether the RAS directly influences the endothelium as well as endothelial proliferation, thus angiogenesis, itself. Methods: Human umbilical vein endothelial cells (HUVEC) were stained for Angiotensin II type 1 receptor (At1R) immunocytochemically and for gene expression of Renin-Angiotensin-System (RAS) components. Angiotensin II dependent regulation of VEGF and Angiopoietins (Ang-1 and Ang-2) was studied using quantitative RealTimePCR. Furthermore, we examined the effect of Angiotensin II on the proliferation of HUVEC using a ki-67 assay and investigated whether administration of At1R blocker candesartan, or VEGF antagonist Flt-1-Fc could suppress Angiotensin II dependent effects. Results: At1R, RAS-components and Ang-1/Ang-2 were expressed in HUVEC. Administration of Angiotensin II increased gene expression of VEGF and decreased the ratio of Ang1/Ang2 expression significantly. In addition, significantly increased endothelial cell proliferation was observed after stimulation with Angiotensin II, which was suppressed by simultaneous administration of candesartan or VEGF antagonist, Flt-1-Fc. Conclusions: These results indicate the potential capacity of Angiotensin II to influence angiogenesis by regulation of angiogenesis associated genes via At1R. Since VEGF blockade opposed the effect of Angiotensin II on cell proliferation, it is hypothesised that VEGF mediates the Angiotensin II-dependent effect in concert with changes in angiopoietin expression. This is the first report of the RAS in regulation of angiogenesis associated genes in endothelial cells indicating an involvement of At1R which may lead to new anti-angiogenic strategies via inhibition of this receptor. No significant financial relationships to disclose.

BACKGROUND: Regulation of tissue remodelling and ovarian permeability by intercellular adhesion complexes may be involved in normal and pathological ovarian function. Therefore, the occurrence, distribution and hormonal control of the adherens junction protein vascular endothelial cadherin (VE-cadherin) and the tight junction proteins occludin and claudin in the human corpus luteum (CL) were investigated. METHODS: CLs from patients undergoing hysterectomy for benign reasons were enucleated during early, mid- and late stages of the functional luteal phase and after HCG rescue in vivo. Immunostaining for occludin, claudins 1 and 5 and VE-cadherin was carried out on fixed tissue. Endothelial cells, granulosa lutein cells and theca lutein cells were identified by reference to serial sections immunostained for CD34, 17α-hydroxylase and 3β-hydroxy-steroid-dehydrogenase. Quantitative analyses were performed using image analyses. RESULTS: Occludin was localized to the plasma membrane of granulosa lutein cells and endothelial cells but was absent in theca lutein cells. Claudin 1 was exclusively localized to the plasma membrane of steroidogenic cells. Claudin 5 and VE-cadherin were only present in endothelial cells. After HCG administration in vivo, adherens and tight junction proteins were significantly down-regulated (P < 0.05). CONCLUSIONS: The decrease of junctional proteins after HCG treatment suggests a hormonal control of tight and adherens junctions in the CL associated with tissue remodelling and an increase in luteal permeability during early pregnancy.

Die Entwicklung eines normalen Gefäßsystems ist eine Voraussetzung für die Funktionsfähigkeit von Organen, da nur über die Blutbahn die Zellen mit Nährstoffen und Sauerstoff versorgt werden. Unter Vaskulogenese versteht man die Entwicklung der großen Stammgefäße im Organismus, die nur während der Embryonalperiode vorkommt, während Angiogenese als die Entwicklung neuer, abzweigender Kapillaren aus vorbestehenden Stammgefäßen definiert wird. Angiogenese findet auch später im ausgewachsenen Organismus vor allem bei Pathologien (Tumorangiogenese, Wundheilung, diabetische Retinopathie, Endometriose) statt. Ansonsten sind die meisten Organgefäßsysteme des Erwachsenen ausgereift, so dass aktive Angiogenese nicht mehr benötigt wird. Eine Ausnahme ist der weibliche Reproduktionstrakt. Als Besonderheit findet hier Angiogenese in monatlichen Zyklen statt, so dass eine übergeordnete hormonelle Kontrolle anzunehmen ist. Die Angiogenese und deren Regulation lassen sich vor allem während der Corpus-luteum-Entwicklung untersuchen, da hier innerhalb weniger Tage ein Organgefäßsystem entsteht, das eine hohe Durchblutung gewährleistet, so dass das Corpus luteum zu den am besten durchbluteten Organen des Organismus gehört. Der Blutfluss im Corpus luteum lässt sich mit malignen Tumoren vergleichen. Dieser Übersichtsartikel beschreibt die Physiologie der angiogenetischen Vorgänge im Corpus luteum und diskutiert die molekularen und hormonellen Regulationsmechanismen mit besonderem Schwerpunkt während der Frühgravidität. The development of a vascular system for the supply of oxygen and nutrients is a prerequisite for normal organ function. Angiogenesis is the development of new capillaries from pre-existing vessels. The vasculature of the adult is normally quiescent except under pathological conditions such as tumour angiogenesis or wound healing. However physiological angiogenesis occurs regularly in the female reproductive tract during the ovulatory cycle. Here, angiogenesis appears to be hormonally controlled. The corpus luteum is a site of intense angiogenesis and, when mature, has the highest blood supply of any organ in the body, which is comparable with malignant tumours. Within a short period, the development of the luteal vasculature is followed either by controlled regression of the microvascular tree in the non-fertile cycle, or by maintenance and stabilisation of the new vasculature in a conceptual cycle. This review focuses on the molecular and hormonal regulation of angiogenesis in the corpus luteum, especially during simulated pregnancy in the human.

Morphological changes in the corpus luteum following natural and induced luteolysis in the marmoset were investigated by light and electron microscop

GnRH antagonists have potential for use in postpartum contraception, as it is likely that they would be effective in maintaining the inhibition of ovulation associated with lactation, but possible effects on the infant by transfer of antagonist via breast milk are unknown. The aim of this study was to establish whether chronic treatment with a GnRH antagonist would prevent ovulation throughout the period of lactation using the marmoset monkey as a model and to evaluate the effects of the presence of GnRH antagonist in breast milk on the postnatal rise in plasma testosterone concentrations in male infants. Mothers who had delivered male twins were selected. Starting within 3 days postpartum, mothers (n = 5/group) were treated with either 6.0 or 0.6 mg/kg of the GnRH antagonist antide, sc, once per week for 11 weeks. Ten postpartum lactating females acted as controls. All animals were housed in family groups with fertile males. To determine possible effects on the postnatal rise in testosterone, plasma samples were collected from the male infants of the high dose antide-treated mothers at weekly intervals for 12 weeks. Plasma progesterone concentrations were monitored in lactating mothers until establishment of pregnancy in both treated and control groups. Concentrations of antide were determined by RIA in plasma from mothers in the high dose group, in their milk, and in pooled plasma samples from their infants. Ovulation followed by pregnancy occurred in all of the control animals. No ovulations occurred during treatment with antide. Antide was present throughout treatment in plasma and breast milk in the mother. In male infants feeding from mothers receiving high dose treatment, antide was not detectable in infant plasma, and plasma testosterone concentrations were within the normal range for male neonates in our colony. These results indicate that the GnRH antagonist has potential as a method of contraception postpartum without affecting the postnatal rise in testosterone in male infants.